The name of Earth's single, huge continent from over 250 million years ago is (1 point) A.Megaland. B.Pangaea. C.Gondwanaland. D.Laurasia. You have new items in your feed. Click to view. Question and answer The name of Earth's single, huge continent from over 250 million years ago is (1 point) A.Megaland. B.Pangaea. C.Gondwanaland. D.Laurasia. The name of the Earth's single continent was B. Pangaea Get an answer The name of Earth's single, huge continent from over 250 million years ago is (1 point) A.Megaland. B.Pangaea. C.Gondwanaland. D.Laurasia. Original conversation User: The name of Earth's single, huge continent from over 250 million years ago is (1 point) A.Megaland. B.Pangaea. C.Gondwanaland. D.Laurasia. Weegy: The name of the Earth's single continent was B.

Pangaea MrG |Points 1812| User: Krystal Weegy: The name of Earth's single, huge continent from over 250 million years ago is B.- Pangaea Expert answered| hhaokok |Points 32| BBC Earth - Supercontinents join nearly all the Earth's dry land Over 200 million years ago, the continents were joined together. Dr Iain Stewart explains how the Earth's moving tectonic plates resulted in a supercontinent called Pangaea. Supercontinents In geology, a supercontinent is the assembly of most or all of Earth's continental blocks or cratons to form a single large landmass. However, the definition of a supercontinent can be ambiguous. Many earth scientists, such as P.F. Hoffman (1999), use the term "supercontinent" to mean "a clustering of nearly all continents". This definition leaves room for interpretation when labeling a continental body and is easier to apply to Precambrian times.

Using the first definition provided here, Gondwana (aka Gondwanaland) is not considered a supercontinent, because the landmasses of Baltica, Laurentia and Siberia also existed at the same time but physically separate from each other. The landmass of Pangaea is the collective name describing all of these continental masses when they were in proximity to one another. This would classify Pangaea as a supercontinent. According to the definition by Rogers and Santosh (2004), a supercontinent does not exist today. Supercontinents have assembled and dispersed multiple times in the geologic past (see table). The positions of continents have been accurately determined back to the early Jurassic. However, beyond 200 Ma, continental positions are much less certain. Facts About Pangaea The breakup of the Pangaea supercontinent. Credit: U.S. Geological Survey About 300 million years ago, Earth didn't have seven continents, but instead one massive supercontinent called Pangaea, which was surrounded by a single ocean called Panthalassa.

The explanation for Pangaea's formation ushered in the modern theory of plate tectonics , which posits that the Earth's outer shell is broken up into several plates that slide over Earth's rocky shell, the mantle. Over the course of the planet's 3.5 billion-year history, several super continents have formed and broken up, a result of churning and circulation in the Earth's mantle , which makes up most of planet's volume. This breakup and formation of supercontinents has dramatically altered the planet's history. "This is what's driven the entire evolution of the planet through time. This is the major backbeat of the planet," said Brendan Murphy, a geology professor at the St. Francis Xavier University, in Antigonish, Nova Scotia. History More than a century ago, the scientist Alfred Wegener proposed the notion of an ancient supercontinent, which he named Pangaea (sometimes spelled Pangea), after putting together several lines of evidence. The first and most obvious was that the "continents fit together like a tongue and groove," something that was quite noticeable on any accurate map, Murphy said. Another telltale hint that Earth's continents were all one land mass comes from the geologic record.

Coal deposits found in Pennsylvania have a similar composition to those spanning across Poland, Great Britain and Germany from the same time period. That indicates that North America and Europe must have once been a single landmass. And the orientation of magnetic minerals in geologic sediments reveals how Earth's magnetic poles migrated over geologic time, Murphy said. In the fossil record, identical plants, such as the extinct seed fern Glossopteris, are found on now widely disparate continents. And mountain chains that now lie on different continents, such as the Appalachians in the United States and the Atlas Mountains in Morocco, were all part of the Central Pangaea Mountains, formed through the collision of the supercontinents Gondwana and Laurussia. Pangaea formed through a gradual process spanning a few hundred million years. Beginning about 480 million years ago, a continent called Laurentia, which includes parts of North America, merged with several other micro-continents to form Euramerica. Euramerica eventually collided with Gondwana, another supercontinent that included Africa, Australia, South America and the Indian subcontinent. About 200 million years ago, the supercontinent began to break up.

Gondwana (what is now Africa, South America, Antarctica, India and Australia) first split from Laurasia (Eurasia and North America). Then about 150 million years ago, Gondwana broke up. India peeled off from Antarctica, and Africa and South America rifted, according to a 1970 article in the Journal of Geophysical Research . Around 60 million years ago, North America split off from Eurasia. Life and climate Having one massive landmass would have made for very different climactic cycles. For instance, the interior of the continent may have utterly dry, as it was locked behind massive mountain chains that blocked all moisture or rainfall, Murphy said. But the coal deposits found in the United States and Europe reveal that parts of the ancient supercontinent near the equator must have been a lush, tropical rainforest, similar to the Amazonian jungle, Murphy said. (Coal forms when dead plants and animals sink into swampy water, where pressure and water transform the material into peat, then coal.) "The coal deposits are essentially telling us that there was plentiful life on land," Murphy told Live Science.

Pangaea existed for 100 million years, and during that time period several animals flourished, including the Traversodontidae , a family of plant-eating animals that includes the ancestors of mammals. During the Permian period , insects such as beetles and dragonflies flourished. But the existence of Pangaea overlapped with the worst mass extinction in history, the Permian-Triassic (P-TR) extinction event. Also called the Great Dying, it occurred around 252 million years ago and caused most species on Earth to go extinct. The early Triassic period saw the rise of archosaurs, a group of animals that eventually gave rise to crocodiles and birds, and a plethora of reptiles. And about 230 million years ago some of the earliest dinosaurs emerged on Pangaea, including theropods, largely carnivorous dinosaurs that mostly had air-filled bones and feathers similar to birds. Cycle in history The current configuration of continents is unlikely to be the last. Supercontinents have formed several times in Earth's history, only to be split off into new continents.

Right now for instance, Australia is inching toward Asia, and the eastern portion of Africa is slowly peeling off from the rest of the continent. Geologists have noticed that there is a quasi-regular cycle in which supercontinents form and break up every 300 to 400 million years, but exactly why is a mystery, Murphy said. But most scientists believe that the supercontinent cycle is largely driven by circulation dynamics in the mantle, according to a 2010 article in the Journal of Geodynamics . Beyond that, the details get fuzzy. While the heat formed in the mantle likely comes from the radioactive decay of unstable elements, such as uranium, scientists don't agree on whether there are mini-pockets of heat flow within the mantle, or if the entire shell is one big heat conveyor belt, Murphy said. Follow Tia Ghose on Twitter and Google+ . Follow LiveScience @livescience , Facebook & Google+ . Additional resources The Pangea Supercontinent By Amanda Briney, Contributing Writer Pangea, also spelled Pangaea, was a supercontinent that existed on the Earth millions of years ago and covered about one-third of its surface.

A supercontinent is a very large landmass that is made up of more than one continent. In the case of Pangea nearly all of the Earth's continents were connected into one large landmass. It is believed that Pangea began forming about 300 million years ago, was fully together by 270 million years ago and began to separate around 200 million years ago. The name Pangea is ancient Greek and means "all lands." The term began being used in the early 20th century after Alfred Wegener noticed that the Earth's continents looked like they fit together like a jigsaw puzzle. He later developed his theory of continental drift to explain why the continents looked the way they did and first used the term Pangea at a symposium in 1927 focused on that topic. Formation of Pangea Due to mantle convection within the Earth's surface new material constantly comes up between the Earth's tectonic plates at rift zones , causing them to move away from the rift and toward one another at the ends.

continue reading below our video 10 Facts About the Titanic That You Don't Know In the case of Pangea, the Earth's continents were eventually moved so much over millions of years that they combined into one large supercontinent. Around 300 million years ago the northwestern part of the ancient continent of Gondwana (near the South Pole), collided with the southern part of the Euramerican continent to form one very large continent. Eventually the Angaran continent, located near the North Pole, began to move south and it collided with the northern part of the Euramerican continent to form the large supercontinent, Pangea, by about 270 million years ago. It should be noted however that there was another separate landmass, Cathaysia, which was made up of north and south China that was not a part of the larger Pangea landmass. Once it was completely formed, Pangea covered around one-third of the Earth's surface and it was surrounded by an ocean that covered the rest of the globe. This ocean was called Panthalassa.

Break-Up of Pangea Pangea began to break up about 200 million years ago as a result of the movement of the Earth's tectonic plates and mantle convection. Just as Pangea was formed by being pushed together due to the movement of the Earth's plates away at rift zones, a rift of new material caused it to separate. Scientists believe that the new rift began due to a weakness in the Earth's crust. At that weak area, magma began to push through and create a volcanic rift zone. Eventually the rift zone grew so large that it formed a basin and Pangea began to separate. In the areas where Pangea began to separate, new oceans formed as Panthalassa rushed into the newly opened areas. The first new oceans to form were the central and southern Atlantic. About 180 million years ago the central Atlantic Ocean opened up between North America and northwestern Africa. Around 140 million years ago the South Atlantic Ocean formed when what is today South America separated from the west coast of southern Africa. The Indian Ocean was the next to form when India separated from Antarctica and Australia and about 80 million years ago North America and Europe separated, Australia and Antarctica separated and India and Madagascar separated.

Over millions more years, the continents gradually moved to their current positions. Evidence for Pangea As Alfred Wegener noticed in the early 20th century, the Earth's continents seem to fit together like a jigsaw puzzle in many areas around the globe. This is the significant evidence for the existence of Pangea millions of years ago. The most prominent place where this is visible is the northwestern coast of Africa and the eastern coast of South America. In that location the two continents look like they were once connected, which they in fact were during Pangea. Other evidence for Pangea includes fossil distribution, distinctive patterns in rock strata in now unconnected parts of the world and the distribution of the world's coal. In terms of fossil distribution, archaeologists have found matching fossil remains if ancient species in continents are separated by thousands of miles of ocean today. For example matching reptile fossils have been found in Africa and South America indicating that these species at one time lived very close to each other as it is not possible to them to have crossed the Atlantic Ocean. Patterns in rock strata are another indicator for the existence of Pangea. Geologists have discovered distinctive patterns in rocks in continents that are now thousands of miles apart.

By having matching patterns it indicates that the two continents and their rocks were at one time one continent. Finally the world's coal distribution is evidence for Pangea. Coal normally forms in warm, wet climates. However geologists have found coal under Antarctica's very cold and dry ice caps. If Antarctica were a part of Pangea it is likely that it would have been in another location on the Earth and the climate when the coal formed would have been very different than it is today. Many Ancient Supercontinents Based on the evidence scientists have found in plate tectonics, it is likely that Pangea was not the only supercontinent to exist on the Earth. In fact, archaeological data found in matching rock types and searching for fossils shows that the formation and break-up of supercontinents like Pangea are a cycle throughout the Earth's history ( Lovett, 2008 ). Gondwana and Rodinia are two supercontinents that scientists have discovered that existed prior to Pangea. Scientists also predict that the cycle of supercontinents will continue.

Currently the world's continents are moving away from the Mid-Atlantic Ridge toward the middle of the Pacific Ocean where they will eventually collide with one another in about 80 million years (Lovett, 2008). To see a diagram of Pangea and how it separated, visit the United States' Geological Survey's Historical Perspective page within This Dynamic Earth . Pangea | supercontinent | Britannica.com supercontinent Pangea, also spelled Pangaea, in early geologic time , a supercontinent that incorporated almost all the landmasses on Earth . Paleogeography and paleoceanography of (top) Early Permian and (bottom) early Late Permian times. Adapted from C.A. Ross and J.R.P. Ross, Cushman Foundation for Foraminiferal Research, Special Publication 24 Pangea was surrounded by a global ocean called Panthalassa, and it was fully assembled by the Early Permian Period (some 299 million to 272 million years ago).

The supercontinent began to break apart about 200 million years ago, during the Early Jurassic Period (201 million to 174 million years ago), eventually forming the modern continents and the Atlantic and Indian ocean s. Pangea’s existence was first proposed in 1912 by German meteorologist Alfred Wegener as a part of his theory of continental drift . Its name is derived from the Greek pangaia, meaning “all the Earth.” The land on Earth is constantly moving. Over millions of years, the continents broke apart from a … Encyclopædia Britannica, Inc. The land and seas on Earth are constantly moving. Over the course of millions of years, the … Created and produced by QA International. © QA International, 2010. All rights reserved. During the Early Permian, the northwestern coastline of the ancient continent Gondwana (a paleocontinent that would eventually fragment to become South America , India , Africa , Australia , and Antarctica ) collided with and joined the southern part of Euramerica (a paleocontinent made up of North America and southern Europe ).

With the fusion of the Angaran craton (the stable interior portion of a continent) of Siberia to that combined landmass during the middle of the Early Permian, the assembly of Pangea was complete. Cathaysia, a landmass comprising the former tectonic plates of North and South China , was not incorporated into Pangea. Rather, it formed a separate, much smaller, continent within the global ocean Panthalassa. Similar Topics Laurasia The mechanism for the breakup of Pangea is now explained in terms of plate tectonics rather than Wegener’s outmoded concept of continental drift, which simply stated that Earth’s continents were once joined together into the supercontinent Pangea that lasted for most of geologic time. Plate tectonics states that Earth’s outer shell, or lithosphere , consists of large rigid plates that move apart at oceanic ridges , come together at subduction zones , or slip past one another along fault lines . The pattern of seafloor spreading indicates that Pangea did not break apart all at once but rather fragmented in distinct stages. Plate tectonics also postulates that the continents joined with one another and broke apart several times in Earth’s geologic history.

The first oceans formed from the breakup, some 180 million years ago, were the central Atlantic Ocean between northwestern Africa and North America and the southwestern Indian Ocean between Africa and Antarctica. The South Atlantic Ocean opened about 140 million years ago as Africa separated from South America. About the same time, India separated from Antarctica and Australia, forming the central Indian Ocean. Finally, about 80 million years ago, North America separated from Europe, Australia began to rift away from Antarctica, and India broke away from Madagascar . India eventually collided with Eurasia approximately 50 million years ago, forming the Himalayas . During Earth’s long history, there probably have been several Pangea-like supercontinents. The oldest of those supercontinents is called Rodinia and was formed during Precambrian time some one billion years ago. Another Pangea-like supercontinent, Pannotia, was assembled 600 million years ago, at the end of the Precambrian. Present-day plate motions are bringing the continents together once again. Africa has begun to collide with southern Europe, and the Australian Plate is now colliding with Southeast Asia .

Within the next 250 million years, Africa and the Americas will merge with Eurasia to form a supercontinent that approaches Pangean proportions. The episodic assembly of the world’s landmasses has been called the supercontinent cycle or, in honour of Wegener, the Wegenerian cycle (see plate tectonics: Supercontinent cycle ). Map showing the future world as projected to appear in about 250 million years. Earth’s present-day … Adapted from C.R. Scotese, The University of Texas at Arlington Learn More in these related articles: The Great Dying | Science Mission Directorate Science Mission Directorate Jan 28, 2002 The Great Dying 250 million years ago something unknown wiped out most life on our planet. Now scientists are finding buried clues to the mystery inside tiny capsules of cosmic gas. Listen to this story via , or get help . January 28, 2002: It was almost the perfect crime. Some perpetrator -- or perpetrators -- committed murder on a scale unequaled in the history of the world. They left few clues to their identity, and they buried all the evidence under layers and layers of earth.

The case has gone unsolved for years -- 250 million years, that is. But now the pieces are starting to come together, thanks to a team of NASA-funded sleuths who have found the "fingerprints" of the villain, or at least of one of the accomplices Above: Life was flourishing on the Earth about 250 million years ago, then during a brief window of geologic time nearly all of it was wiped out. This image is an artist's impression of a Lower Permian swamp in Texas. Sign up for EXPRESS SCIENCE NEWS delivery The terrible event had been lost in the amnesia of time for eons. It was only recently that paleontologists, like hikers stumbling upon an unmarked grave in the woods, noticed a startling pattern in the fossil record: Below a certain point in the accumulated layers of earth, the rock shows signs of an ancient world teeming with life. In more recent layers just above that point, signs of life all but vanish . Somehow, most of the life on Earth perished in a brief moment of geologic time roughly 250 million years ago.

Scientists call it the Permian-Triassic extinction or "the Great Dying" -- not to be confused with the better-known Cretaceous-Tertiary extinction that signaled the end of the dinosaurs 65 million years ago. Whatever happened during the Permian-Triassic period was much worse: No class of life was spared from the devastation. Trees, plants, lizards, proto-mammals, insects, fish, mollusks, and microbes -- all were nearly wiped out. Roughly 9 in 10 marine species and 7 in 10 land species vanished. Life on our planet almost came to an end. Scientists have suggested many possible causes for the Great Dying: severe volcanism, a nearby supernova, environmental changes wrought by the formation of a super-continent, the devastating impact of a large asteroid -- or some combination of these. Proving which theory is correct has been difficult. The trail has grown cold over the last quarter billion years; much of the evidence has been destroyed. Left: The Earth was engulfed in widespread volcanism at the time of the extinction. Photo courtesy Dick Rasp/National Park Service.

"These rocks have been through a lot, geologically speaking, and a lot of times they don't preserve the (extinction) boundary very well," says Luann Becker, a geologist at the University of California, Santa Barbara. Indeed, there are few 250 million-year-old rocks left on Earth. Most have been recycled by our planet's tectonic activity. Undaunted, Becker led a NASA-funded science team to sites in Hungary, Japan and China where such rocks still exist and have been exposed. There they found telltale signs of a collision between our planet and an asteroid 6 to 12 km across -- in other words, as big or bigger than Mt. Everest. Many paleontologists have been skeptical of the theory that an asteroid caused the extinction. Early studies of the fossil record suggested that the die-out happened gradually over millions of years -- not suddenly like an impact event. But as their methods for dating the disappearance of species has improved, estimates of its duration have shrunk from millions of years to between 8,000 and 100,000 years. That's a blink of the eye in geological terms.

"I think paleontologists are now coming full circle and leading the way, saying that the extinction was extremely abrupt," Becker notes. "Life vanished quickly on the scale of geologic time, and it takes something catastrophic to do that." Such evidence is merely circumstantial -- it doesn't actually prove anything. Becker's evidence, however, is more direct and persuasive: Deep inside Permian-Triassic rocks, Becker's team found soccer ball-shaped molecules called "fullerenes" (or "buckyballs") with traces of helium and argon gas trapped inside. The fullerenes held an unusual number of 3He and 36Ar atoms -- isotopes that are more common in space than on Earth. Something, like a comet or an asteroid, must have brought the fullerenes to our planet. Above: The carbon atoms in a fullerene molecule are arranged in a spherical pattern similar to a geodesic dome. (Geodesic domes were invented by Buckminster Fuller, hence the name of the molecules.) This shape allows the fullerenes to trap gases inside. Image courtesy Luann Becker.

Becker's team had previously found such gas-bearing buckyballs in rock layers associated with two known impact events: the 65 million-year-old Cretaceous-Tertiary impact and the 1.8 billion-year-old Sudbury impact crater in Ontario, Canada. They also found fullerenes containing similar gases in some meteorites. Taken together, these clues make a compelling case that a space rock struck the Earth at the time of the Great Dying. But was an asteroid the killer, or merely an accomplice? Many scientists believe that life was already struggling when the putative space rock arrived. Our planet was in the throes of severe volcanism. In a region that is now called Siberia, 1.5 million cubic kilometers of lava flowed from an awesome fissure in the crust. (For comparison, Mt. St. Helens unleashed about one cubic kilometer of lava in 1980.) Such an eruption would have scorched vast expanses of land, clouded the atmosphere with dust, and released climate-altering greenhouse gases. Above: What the world looked like 250 million years ago. Image credit: Chris Scotese . [ more ] World geography was also changing then.

Plate tectonics pushed the continents together to form the super-continent Pangea and the super-ocean Panthalassa. Weather patterns and ocean currents shifted, many coastlines and their shallow marine ecosystems vanished, sea levels dropped. "If life suddenly has all these different things happen to it," Becker says, "and then you slam it with a rock the size of Mt. Everest -- boy! That's just really bad luck." Was the "crime" then merely an accident? Perhaps so. Nevertheless, it's wise to identify the suspects -- an ongoing process -- before it happens again. Editor's note: Becker's colleagues include Robert Poreda and Andrew Hunt from the University of Rochester, NY; Ted Bunch of the NASA Ames Research Center; and Michael Rampino of New York University and NASA's Goddard Institute of Space Sciences. Funding for the research was provided by NASA's Astrobiology and Cosmochemistry programs and the National Science Foundation. Web Links NASA Astrobiology Institute -- home page What happens when a 6 to 12 km space rock hits Earth? The initial blast from the impact would sweep over a large area of the planet, killing everything in its path.

It would throw up millions of tons of debris to obscure the Sun, hindering the photosynthesis that drives most ecosystems. The heat would release large volumes of CO2 and SO2 from the vaporization of rocks, and ignite the world's forests -- releasing still more CO2 and inducing long-term global warming. As the atmospheric debris slowly rains back down onto the surface, toxic compounds might poison much of what life remains. Right: Artist Don Davis's rendition of a large asteroid striking Earth. Mounting Evidence: A research team headed by Kunio Kaiho of the Tohoku University in Sendai, Japan, recently announced their measurements of sulfur isotopes in rocks from the Permian-Triassic boundary. The P-T boundary layer is enriched with "light sulfur" -- much like material from our planet's mantle. The finding suggests that some event 250,000,000 years ago (like an asteroid impact) spread material from the mantle over the surface of the land.

"Their data suggest that an asteroid or comet hit the ocean and caused a rapid, massive release of sulfur and other noxious materials from the Earth's mantle to the ocean-atmosphere system," agrees Ted Bunch, a research scientist at NASA's Ames Research Center and a member of Becker's science team. Reference: "End-Permian catastrophe by a bolide impact: Evidence of a gigantic release of sulfur from the mantle," K. Kaiho, et al., Geology, Sept. 2001, 29, 815. Massive Volcanic Eruptions in Siberia Linked with Mass Extinction -- scientists present evidence linking the largest extinction of animals in Earth's history with rapid and extensive volcanic activity in Siberia Earth Movements - Qld Science Teachers Earth Movements Interior Structure of the Earth The Crust The crust on which we are is approximately 64 km thick under land areas to as little as 12 km thick under sea areas. The upper layer of the crust is made mostly of silicon and aluminium, and is rigid. The lower layer of the crust is made of silicon and magnesium, and is plastic.

The Mantle The mantle is beneath the crust, and is about 3 000 km thick. It is made of mostly iron and magnesium. It is plastic like putty, and continually changes shape due to heat and pressure. The Core The core extends from 3 000 km beneath the Earth's surface to the centre of the Earth. The outer layer of the core is liquid molten rock, and is about 2 000 km thick. The inner layer of the core is solid rock, and is about 1 500 km thick. The core is mostly iron, nickel and cobalt. Crustal Plates North American Plate Convergent Plate Boundaries Where plates move towards each other or past each other, great tension results. This tension builds up until the plates slide past or under each other, during an Earthquake Divergent Plate Boundaries Where plates move away from each other, molten rock (magma) from deep beneath the crust oozes out through the space between the plates forming a Volcano.

Theory of Plate Tectonics Theory of Continental Drift - In 1912, Alfred Wegener noticed the similarities between the coastline shapes and the fossils of continents such as Africa and South America. He suggested that the continents may have once been joined together in a large super-continent, and had since drifted to their present positions. Theory of Plate Tectonics - This is the present well-accepted idea that where the plates move towards each other, earthquakes occur, and where the plates move away from each other, volcanoes occur. For these to occur, there are slow-moving convection currents within the mantle. This is supported by exploration of the Atlantic Ocean floor, and laser measurements showing the distances between continents changing by a few centimetres a year. Pangaea - Pangaea was the name given to the one large super-continent that may have existed up till 200 million years ago before dinosaurs roamed the Earth. Laurasia and Gondwana - About 200 million years ago, Pangaea may have split into two smaller super-continents. The northern hemisphere super-continent with Europe, northern Asia and North America was called Laurasia.

The southern hemisphere super-continent with Africa, southern Asia, Australia, Antarctica and South America was called Gondwana. Then, many millions of years later, the continents as we know them, drifted to their present positions. Volcanoes Volcanoes are mountains or hills formed around a vent in the Earth's crust through which hot molten rock (magma) is expelled. When the magma reaches the Earth's surface, it is called lava. The lava cools, solidifies and accumulates around the vent, building a cone. 3 Igneous Rocks Granite - volcanic rock with large crystals formed by slow cooling of magma beneath the Earth's surface Basalt - volcanic rock with small crystals formed by rapid cooling of lava on the Earth's surface Pumicestone - volcanic rock filled with air bubbles formed by the ejection and rapid cooling of lava in the air After the Eruption A crater lake may form when rain fills the cooled volcanic crater. If the volcano sides erode over time leaving the solid vent, mountains such as the Glasshouse Mountains are formed. If a volcano has not erupted in a long time but may erupt again, it is said to be dormant (sleeping).

If a volcano has not erupted in a very long time and probably will not erupt again, it is called extinct. Types of Volcanoes Shield Cone - Wide at the base with gentle slopes, formed by gentle volcanoes Cinder Cone - Narrow at the base, steep slopes built up by angular interlocking cinders (ash), formed by explosive volcanoes Composite Cone - Intermediate between the shield and cinder cones, built up from alternating layers of lava and cinder Dome Mountain - Magma pushes up through sedimentary rock Earthquakes Earthquakes are shocks caused by moving plates. Shock waves are produced from a stress point deep beneath the Earth's surface and become less intense the further they travel.

Focus - the point deep beneath the Earth's surface where an earthquake starts Epicentre - the point directly above the focus on the Earth's surface, where most damage occurs Seismograph - an instrument to detect and record the vibrations of the Earth's crust 3 Types of Vibrations or Shock Waves P Waves - Primary or push waves that travel deep beneath the Earth's surface at about 5.5 to 13.5 km/s S Waves - Secondary or shake waves that travel deep beneath the Earth's surface at about 3.7 to 7 km/s L Waves - Longitudinal waves that travel along the Earth's surface at about 3.2 km/s, causing greatest damage to buildings, landslides and tsunamis (tidal waves) The Richter Scale - This scale was devised in 1935 to measure the magnitude of an earthquake on a scale from 0 (almost unnoticed quake) to 10 (HUGE quake). Each number on the scale has 10 times more intensity than the previous one. The Modified Mercalli Scale - This scale describes an earthquake's damage from 1 to 12. Folding Folding is the buckling of rock layers due to lateral earth forces.

Anticlines are the crests or tops of folds. Synclines are the troughs or bottoms of folds. Faulting Faulting occurs when intense stretching or pushing forces occur along a break in the Earth's crust. The break is called a fault. Unconformity An unconformity is a surface that separates two layers or strata, and represents an interval of time in which deposition stopped, erosion removed some sediments and rock, and then deposition resumed. On this page: continent - National Geographic Society continent This map beautifully illustrates the continent of Australia. Map by Sean O'Connor Microcontinents In addition to the seven major continents, Earth is home to microcontinents, or pieces of land that are not geologically identified with a continent.

Major microcontinents include: Zealandia, in the South Pacific Ocean, whose land includes New Zealand and New Caledonia Madagascar, in the South Indian Ocean the Mascarene Plateau, in the South Indian Ocean, whose lands include the Seychelles and Reunion islands the Kerguelen Plateau, in the South Indian Ocean, whose lands include the Kerguelen Islands, a territory of France Jan Mayen, in the North Atlantic Ocean, a Norwegian island A continent is one of Earth’s seven main divisions of land. The continents are, from largest to smallest: Asia, Africa, North America, South America, Antarctica, Europe, and Australia. When geographer s identify a continent, they usually include all the island s associated with it. Japan, for instance, is part of the continent of Asia. Greenland and all the islands in the Caribbean Sea are usually considered part of North America. Together, the continents add up to about 148 million square kilometers (57 million square miles) of land. Continents make up most—but not all—of the Earth’s land surface. A very small portion of the total land area is made up of islands that are not considered physical parts of continents.

New Zealand, French Polynesia, and the Hawaiian Islands are examples of land areas that are considered microcontinent s. These areas are usually grouped with culturally similar continents, but are geologic ally distinct . The ocean , divided into four major bodies of water, covers almost three-fourths of the Earth. The area of the ocean is more than double the area of all the continents combined. All continents border at least two oceans. Asia, the largest continent, has the longest series of coastline s.< Coastlines, however, do not indicate the actual boundaries of the continents. Continents are defined by their continental shelves. A continental shelf is a gently sloping area that extends outward from the beach far into the ocean. A continental shelf is part of the ocean, but also part of the continent. If continental shelves were included in the total land area, continents would make up more than one-third of the Earth’s surface. “Continent” has more than just a physical definition. To human geographers, the term is about culture . The continents of Europe and Asia, for example, are actually part of a single, enormous piece of land called Eurasia. But linguistic ally and ethnically, the areas of Asia and Europe are distinct.

The various cultural groups of Europe have more in common with one another than they do with cultural groups in Asia. Because of this, most geographers divide Eurasia into Europe and Asia. An imaginary line, running from the northern Ural Mountains in Russia south to the Caspian and Black Seas, separates Europe, to the west, from Asia, to the east. Building the Continents The Earth formed 4.6 billion years ago from a great, swirling cloud of dust and gas . The continuous smashing of space debris and the pull of gravity made the inside of the Earth heat up. As the heat increased, some of the Earth’s rocky materials melted and rose to the surface, where they cooled and formed a crust. Heavier material sank toward the Earth’s center. Eventually, the Earth came to have three main layers: the core , the mantle , and the crust . The crust and the top portion of the mantle form a rigid shell around the Earth that is broken up into huge sections called tectonic plate s. The heat from inside the Earth causes the plates to slide around on the molten mantle. Today, tectonic plates continue to slowly slide around the surface, just as they have been doing for hundreds of millions of years.

Geologist s believe the interaction of the plates, a process called plate tectonics , contributed to the creation of continents. Studies of rocks found in ancient areas of North America have revealed that the oldest known pieces of the continents began to form nearly 4 billion years ago, soon after the Earth itself formed. At that time, a primitive ocean covered Earth. Only a small fraction of the crust was made up of continental material. Scientists theorize that this material built up along the boundaries of tectonic plates during a process called subduction . During subduction, plates collide, and the edge of one plate slides beneath the edge of another. When heavy oceanic crust subduct ed toward the mantle, it melted in the mantle’s intense heat. Once melted, the rock became lighter. Called magma , it rose through the overlying plate and burst out as lava . When the lava cooled, it hardened into igneous rock . Gradually, the igneous rock built up into small volcanic island s above the surface of the ocean. Over time, these islands grew bigger, partly as the result of more lava flows and partly from the buildup of material scraped off descending plates. When plates carrying islands subducted, the islands themselves did not descend into the mantle.

Their material fuse d with that of islands on the neighboring plate. This made even larger landmasses—the first continents. The building of volcanic islands and continental material through plate tectonics is a process that continues today. Continental crust is much lighter than oceanic crust. In subduction zone s, where tectonic plates interact with each other, oceanic crust always subducts beneath continental crust. Oceanic crust is constantly being recycled in the mantle. For this reason, continental crust is much, much older than oceanic crust. Wandering Continents If you could visit the Earth as it was millions of years ago, it would look very different. The continents have not always been where they are today. About 480 million years ago, most continents were scattered chunks of land lying along or below the Equator . Millions of years of continuous tectonic activity changed their positions, and by 240 million years ago, almost all of the world’s land was joined in a single, huge continent. Geologists call this supercontinent Pangaea , which means “all lands” in Greek. By about 200 million years ago, the forces that helped form Pangaea caused the supercontinent to begin to break apart.

The pieces of Pangaea that began to move apart were the beginnings of the continents that we know today. A giant landmass that would become Europe, Asia, and North America separated from another mass that would split up into other continents. In time, Antarctica and Australia, still joined together, broke away and drifted south. The small piece of land that would become the peninsula of India broke away and for millions of years moved north as a large island. It eventually collided with Asia. Gradually, the different landmasses moved to their present locations. The positions of the continents are always changing. North America and Europe are moving away from each other at the rate of about 2.5 centimeters (1 inch) per year. If you could visit the planet in the future, you might find that part of the U.S. state of California had separated from North America and become an island. Africa might have split in two along the Great Rift Valley. It is even possible that another supercontinent may form some day. Continental Features The surface of the continents has changed many times because of mountain building, weathering , erosion , and build-up of sediment . Continuous, slow movement of tectonic plates also changes surface features.

The rocks that form the continents have been shaped and reshaped many times. Great mountain range s have risen and then have been worn away. Ocean waters have flood ed huge areas and then gradually dried up. Massive ice sheet s have come and gone, sculpting the landscape in the process. Today, all continents have great mountain ranges, vast plain s, extensive plateau s, and complex river system s. The landmasses’ average elevation above sea level is about 838 meters (2,750 feet). Although each is unique , all the continents share two basic features: old, geologically stable regions, and younger, somewhat more active region s. In the younger regions, the process of mountain building has happened recently and often continues to happen. The power for mountain building, or orogeny , comes from plate tectonics. One way mountains form is through the collision of two tectonic plates. The impact creates wrinkles in the crust, just as a rug wrinkles when you push against one end of it. Such a collision created Asia’s Himalaya Mountains several million years ago. The plate carrying India slowly and forcefully shoved the landmass of India into Asia, which was riding on another plate.

The collision continues today, causing the Himalayas to grow taller every year. Recently formed mountains, called coastal range s, rise near the western coasts of North and South America. Older, more stable mountain ranges are found in the interior of continents. The Appalachians of North America and the Urals, on the border between Europe and Asia, are older mountain ranges that are not geologically active. Even older than these ancient, eroded mountain ranges are flatter, more stable areas of the continents called craton s. A craton is an area of ancient crust that formed during the Earth’s early history. Every continent has a craton. Microcontinents, like New Zealand, lack cratons. Cratons have two forms: shield s and platform s. Shields are bare rocks that may be the roots or cores of ancient mountain ranges that have completely eroded away. Platforms are cratons with sediment and sedimentary rock lying on top. The Canadian Shield makes up about a quarter of North America. For hundreds of thousands of years, sheets of ice up to 3.2 kilometers (2 miles) thick coated the Canadian Shield. The moving ice wore away material on top of ancient rock layers, exposing some of the oldest formations on Earth.

When you stand on the oldest part of the Canadian Shield, you stand directly on rocks that formed more than 3.5 billion years ago. North America North America, the third-largest continent, extends from the tiny Aleutian Islands in the northwest to the Isthmus of Panama in the south. The continent includes the enormous island of Greenland in the northeast. In the far north, the continent stretches halfway around the world, from Greenland to the Aleutians. But at Panama’s narrowest part, the continent is just 50 kilometers (31 miles) across. Young mountains—including the Rockies, North America’s largest chain—rise in the West. Some of the Earth’s youngest mountains are found in the Cascade Range of the U.S. states of Washington, Oregon, and California. Some peaks there began to form only about a million years ago—a wink of an eye in Earth’s long history. North America’s older mountain ranges rise near the East Coast of the United States and Canada. In between the mountain systems lie wide plains that contain deep, rich soil . Much of the soil was formed from material deposited during the most recent glacial period . This ice age reached its peak about 18,000 years ago.

As glacier s retreated, streams of melted ice dropped sediment on the land, building layers of fertile soil in the plains region. Grain grown in this region, called the “breadbasket of North America,” feeds a large part of the world. North America contains a variety of natural wonders. Landforms and all types of vegetation can be found within its boundaries. North America has deep canyon s, such as Copper Canyon in the Mexican state of Chihuahua. Yellowstone National Park, in the U.S. state of Wyoming, has some of the world’s most active geyser s. Canada’s Bay of Fundy has the greatest variation of tide levels in the world. The Great Lakes form the planet’s largest area of freshwater . In the U.S. state of California, giant sequoia s, the world’s most massive trees, grow more than 76 meters (250 feet) tall and nearly 31 meters (100 feet) around. Greenland, off the east coast of Canada, is the world’s largest island. Despite its name, Greenland is mostly covered with ice. Its ice is a remnant of the great ice sheets that once blanket ed much of the North American continent.

Greenland is the only place besides Antarctica that still has an ice sheet. From the freezing Arctic to the tropical jungle s of Central America, North America enjoys more climate variation than any other continent. Almost every type of ecosystem is represented somewhere on the continent, from coral reef s in the Caribbean to Greenland’s ice sheet to the Great Plains in the U.S. and Canada. Today, North America is home to the citizens of Canada, the United States, Greenland, Mexico, Belize, Costa Rica, El Salvador, Guatemala, Honduras, Nicaragua, Panama, and the island countries and territories that dot the Caribbean Sea and the western North Atlantic Ocean. Most of North America sits on the North American Plate. Parts of the Canadian province of British Columbia and the U.S. states of Washington, Oregon, and California sit on the tiny Juan de Fuca Plate. Parts of California and the Mexican state of Baja California sit on the enormous Pacific Plate. Parts of Baja California and the Mexican states of Baja California Sur, Sonora, Sinaloa, and Jalisco sit on the Cocos Plate. The Caribbean Plate carries most of the small islands of the Caribbean Sea (south of the island of Cuba) as well as Central America from Honduras to Panama.

The Hawaiian Islands, in the middle of the Pacific Ocean on the Pacific Plate, are usually considered part of North America. South America South America is connected to North America by the narrow Isthmus of Panama. These two continents weren’t always connected; they came together only 3 million years ago. South America is the fourth-largest continent and extends from the sunny beaches of the Caribbean Sea to the frigid waters near the Antarctic Circle. South America’s southernmost islands, called Tierra del Fuego , are less than 1,120 kilometers (700 miles) from Antarctica. These islands even host some Antarctic birds, such as penguins, albatrosses, and terns. Early Spanish explorer s visiting the islands for the first time saw small fires dotting the land. These fires, made by indigenous people, seemed to float on the water, which is probably how the islands got their name—Tierra del Fuego means "Land of Fire." The Andes, the Earth’s longest terrestrial mountain range, stretch the entire length of South America. Many active volcano es dot the range. These volcanic areas are fueled by heat generated as a large oceanic plate, called the Nazca Plate, grinds beneath the plate carrying South America.

The central-southern area of South America has pampas , or plains. These rich areas are ideal for agriculture . The growing of wheat is a major industry in the pampas. Grazing animal s, such as cattle and sheep, are also raised in the pampas region. In northern South America, the Amazon River and its tributaries flow through the world’s largest tropical rain forest . In volume, the Amazon is the largest river in the world. More water flows from it than from the next six largest rivers combined. South America is also home to the world’s tallest waterfall , Angel Falls, in the country of Venezuela. Water flows more than 979 meters (3,212 feet)—almost a mile. The falls are so high that most of the water evaporate s into mist or is blown away by wind before it reaches the ground. South American rain forests contain an enormous wealth of animal and plant life. More than 15,000 species of plants and animals are found only in the Amazon River basin . Many Amazonian plant species are sources of food and medicine for the rest of the world.

Scientists are trying to find ways to preserve this precious and fragile environment as people move into the Amazon basin and clear land for settlements and agriculture. Twelve independent countries make up South America: Brazil, Colombia, Argentina, Peru, Venezuela, Chile, Ecuador, Bolivia, Paraguay, Uruguay, Guyana, and Suriname. The territories of French Guiana, part of France, and the Falkland Islands, part of the United Kingdom, are also part of South America. Almost all of South America sits on top of the South American Plate. Europe Europe, the sixth-largest continent, contains just 7 percent of the world’s land. In total area, the continent of Europe is only slightly larger than the country of Canada. However, the population of Europe is more than twice that of South America. Europe has more than 40 countries and many of the world’s major cities, including London, England; Paris, France; Berlin, Germany; Rome, Italy; Madrid, Spain; and Moscow, Russia. Most European countries have access to the ocean. The continent is bordered by the Arctic Ocean in the north, the Atlantic Ocean in the west, the Caspian Sea in the southeast, and the Mediterranean and Black Seas in the south.

The nearness of these bodies of water and the navigation of many of Europe’s rivers played a major role in the continent’s history. Early Europeans learned the river systems of the Volga, Danube, Don, Rhine, and Po, and could successfully travel the length and width of the small continent for trade , communication , or conquest . Navigation and exploration outside of Europe was an important part of the development of the continent’s economic , social, linguistic, and political legacy . European explorers were responsible for colonizing land on every continent except Antarctica. This colonization process had a drastic impact on the economic and political development of those continents, as well as Europe. In the east, the Ural Mountains separate Europe from Asia. The nations of Russia and Kazakhstan straddle both continents. Another range, the Kjølen Mountains, extends along the northern part of the border between Sweden and Norway. To the south, the Alps form an arc stretching from Albania to Austria, then across Switzerland and northern Italy into France. As the youngest and steepest of Europe’s mountains, the Alps geologically resemble the Rockies of North America, another young range. A large area of gently rolling plains extends from northern France eastward to the Urals.

A climate of warm summers, cold winters, and plentiful rain helps make much of this European farmland very productive. The climate of Western Europe, especially around the Mediterranean Sea, makes it one of the world’s leading tourism destinations. Almost all of Europe sits on the massive Eurasian Plate. Africa Africa, the second-largest continent, covers an area more than three times that of the United States. From north to south, Africa stretches about 8,000 kilometers (5,000 miles). It is connected to Asia by the Isthmus of Suez in Egypt. The Sahara, which covers much of North Africa, is the world’s largest hot desert . The world’s longest river, the Nile, flows more than 6,560 kilometers (4,100 miles) from its most remote headwater s in Lake Victoria to the Mediterranean Sea in the north. A series of falls and rapids along the southern part of the river makes navigation difficult. The Nile has played an important role in the history of Africa. In ancient Egyptian civilization , it was a source of life for food , water, and transportation. The top half of Africa is mostly dry, hot desert.

The middle area has savanna s, or flat, grassy plains. This region is home to wild animals such as lions, giraffes, elephants, hyenas, cheetahs, and wildebeests. The central and southern areas of Africa are dominate d by rain forests. Many of these forests thrive around Africa’s other great rivers, the Zambezi, the Congo, and the Niger. However, trees are being cut down in Africa’s rain forests for many of the same reasons deforestation is taking place in the rain forests of South America and Asia: development for businesses, homes, and agriculture. Much of Africa is a high plateau surrounded by narrow strips of coastal lowlands. Hilly uplands and mountains rise in some areas of the interior. Glaciers on Mount Kilimanjaro in Tanzania sit just miles from the tropical jungles below. Even though Kilimanjaro is not far from the Equator, snow covers its summit all year long. In eastern Africa, a giant depression called the Great Rift Valley runs from the Red Sea to the country of Mozambique. (The rift valley actually starts in southwestern Asia.) The Great Rift Valley is a site of major tectonic activity, where the continent of Africa is splitting into two.

Geologists have already named the two parts of the African Plate. The Nubian Plate will carry most of the continent, to the west of the rift; the Somali Plate will carry the far eastern part of the continent, including the so-called “ Horn of Africa .” The Horn of Africa is a peninsula that resembles the upturned horn of a rhinoceros. The countries of Eritrea, Ethiopia, Djibouti, and Somalia sit on the Horn of Africa and the Somali Plate. Africa is home to 56 countries but only 14 percent of the world’s total population. The area of central-eastern Africa is important to scientists who study evolution and the earliest origins of humanity. This area is thought to be the place where hominid s began to evolve. The entire continent of Africa sits on the African Plate. Asia Asia, the largest continent, stretches from the eastern Mediterranean Sea to the western Pacific Ocean. There are more than 40 countries in Asia. Some are among the most-populated countries in the world, including China, India, and Indonesia. Sixty percent of the Earth’s population lives in Asia. More than a third of the world’s people live in China and India alone.

The continent of Asia includes many islands, some of them countries. The Philippines, Indonesia, Japan, and Taiwan are major island nations in Asia. Most of Asia’s people live in cities or fertile farming areas near river valley s, plains, and coasts. The plateaus in central Asia are largely unsuitable for farming and are thinly populated. Asia accounts for almost a third of the world’s land. The continent has a wide range of climate regions, from polar in the Siberia n Arctic to tropical in equatorial Indonesia. Parts of central Asia, including the Gobi Desert in China and Mongolia, are dry year-round. Southeast Asia, on the other hand, depends on the annual monsoon s, which bring rain and make agriculture possible. Monsoon rains and snowmelt feed Asian rivers such as the Ganges, the Yellow, the Mekong, the Indus, and the Yangtze. The rich valley between the Tigris and Euphrates rivers in western Asia is called the “ Fertile Crescent ” for its place in the development of agriculture and human civilization. Asia is the most mountainous of all the continents. More than 50 of the highest peaks in the world are in Asia.

Mount Everest, which reaches more than 8,700 meters (29,000 feet) high in the Himalaya range, is the highest point on Earth. These mountains have become major destination spots for adventurous travelers. Plate tectonics continuously push the mountains higher. As the landmass of India pushes northward into the landmass of Eurasia, parts of the Himalayas rise at a rate of about 2.5 centimeters (1 inch) every five years. Asia contains not only the Earth’s highest elevation, but also its lowest place on land: the shores of the Dead Sea in the countries of Israel and Jordan. The land there lies more than 390 meters (1,300 feet) below sea level. Although the Eurasian Plate carries most of Asia, it is not the only one supporting major parts of the large continent. The Arabian Peninsula, in the continent’s southwest, is carried by the Arabian Plate. The Indian Plate supports the Indian peninsula, sometimes called the Indian subcontinent . The Australian Plate carries some islands in Indonesia. The North American Plate carries eastern Siberia and the northern islands of Japan.

Australia In addition to being the smallest continent, Australia is the flattest and the second-driest, after Antarctica. The continent is sometimes called Oceania, to include the thousands of tiny islands of the Central and South Pacific, most notably Melanesia, Micronesia, and Polynesia (including the U.S. state of Hawaii). However, the continent of Australi itself includes only the nation of Australia, the eastern portion of the island of New Guinea (the nation of Papua New Guinea) and the island nation of New Zealand. Australia covers just fewer than 8.5 million square kilometers (about 3.5 million square miles). Its population is about 31 million. It is the most sparse ly populated continent, after Antarctica. A plateau in the middle of mainland Australia makes up most of the continent’s total area. Rainfall is light on the plateau, and not many people have settled there. The Great Dividing Range, a long mountain range, rises near the east coast and extends from the northern part of the territory of Queensland through the territories of New South Wales and Victoria. Mainland Australia is known for the Outback , a desert area in the interior.

This area is so dry, hot, and barren that few people live there. In addition to the hot plateaus and deserts in mainland Australia, the continent also features lush equatorial rain forests on the island of New Guinea, tropical beaches, and high mountain peaks and glaciers in New Zealand. Most of Australia’s people live in cities along the southern and eastern coasts of the mainland. Major cities include Perth, Sydney, Brisbane, Melbourne, and Adelaide, all in Australia. Biologists who study animals consider Australia a living laboratory. When the continent began to break away from Antarctica more than 60 million years ago, it carried a cargo of animals with it. Isolated from life on other continents, the animals developed into creatures unique to Australia, such as the koala, the platypus, and the Tasmanian devil. The Great Barrier Reef, off mainland Australia’s northeast coast, is another living laboratory. The world’s largest coral reef ecosystem, it is home to thousands of species of fish, sponges, marine mammals, corals, and crustacean s. The reef itself is 1,920 kilometers (1,200 miles) of living coral communities.

By some estimates, it is the world’s largest living organism. Most of Australia sits on the Australian Plate. The southern part of the South Island of New Zealand sits on the Pacific Plate. Antarctica Antarctica is the windiest, driest, and iciest place on Earth. Antarctica is larger than Europe or Australia, but unlike those continents, it has no permanent population. People who work there are scientific research ers and support staff, such as pilots and cooks. The climate of Antarctica makes it impossible to support agriculture or a permanent civilization. Temperatures in Antarctica, much lower than Arctic temperatures, plunge lower than -73 degrees Celsius (-100 degrees Fahrenheit). Scientific bases and laboratories have been established in Antarctica for studies in fields that include geology , oceanography , and meteorology . The freezing temperatures of Antarctica make it an excellent place to study the history of Earth’s atmosphere and climate. Ice core s from the massive Antarctic ice sheet have recorded changes in Earth’s temperature and atmospheric gases for thousands of years. Antarctica is also an ideal place for discovering meteorite s, or stony objects that have impacted the Earth from outer space.

The dark meteorites, often made of metals like iron, stand out from the white landscape of most of the continent. Antarctica is almost completely covered with ice, sometimes as thick as 3.2 kilometers (2 miles). In winter, Antarctica’s surface area may double as pack ice builds up in the ocean around the continent. Like all other continents, Antarctica has volcanic activity. The most active volcano is Mount Erebus, which is less than 1,392 kilometers (870 miles) from the South Pole. Its frequent eruptions are evidence of hot, molten rock beneath the continent’s icy surface. Antarctica does not have any countries. However, scientific groups from different countries inhabit the research stations. A multinational treaty negotiated in 1959 and reviewed in 1991 states that research in Antarctica can only be used for peaceful purposes. McMurdo Station, the largest community in Antarctica, is operated by the United States. Vostok Station, where the coldest temperature on Earth was recorded, is operated by Russia. All of Antarctica sits on the Antarctic Plate. Term agriculture Noun line of latitude at 66.5 degrees south that encircles the continent of Antarctica.

arc part of the outline of a circle. atmosphere bay Noun body of water partially surrounded by land, usually with a wide mouth to a larger body of water. goods carried by a ship, plane, or other vehicle. cattle region that connects North America and South America, including the Isthmus of Panama. civilization coastal range Noun recently formed mountains found near the coast of continents, especially the western coasts of the Americas. coastline outer boundary of a shore. colonize to establish control of a foreign land and culture. communication sharing of information and ideas. complex thick layer of Earth that sits beneath continents. continental shelf tiny ocean animal, some of which secrete calcium carbonate to form reefs. coral reef rocky ocean features made up of millions of coral skeletons. core old, stable part of continental crust, made up of shields and platforms. crust crustacean Noun type of animal (an arthropod) with a hard shell and segmented body that usually lives in the water. culture learned behavior of people, including their languages, belief systems, social structures, institutions, and material goods. debris remains of something broken or destroyed; waste, or garbage. deforestation destruction or removal of forests and their undergrowth.

descend to go from a higher to a lower place. desert Noun construction or preparation of land for housing, industry, or agriculture. distinct dust Noun microscopic particles of rocks or minerals drifting in space. Also called cosmic dust or space dust. economic having to do with money. ecosystem landmass including the continents of Europe and Asia. evaporate to change from a liquid to a gas or vapor. evolution change in heritable traits of a population over time. exploration study and investigation of unknown places, concepts, or issues. explorer person who studies unknown areas. extensive able to produce crops or sustain agriculture. Fertile Crescent region extending from the eastern Mediterranean coast through Southwest Asia to the Persian Gulf. flood water that is not salty. frigid to combine or meld together. gas Noun state of matter with no fixed shape that will fill any container uniformly. Gas molecules are in constant, random motion. geographer person who studies places and the relationships between people and their environments. geologic having to do with the physical formations of the Earth. geologist person who studies the physical formations of the Earth.

geology Noun study of the physical history of the Earth, its composition, its structure, and the processes that form and change it. geyser largest species of tree on Earth. glacial period time of long-term lowering of temperatures on Earth. Also known as an ice age. glacier physical force by which objects attract, or pull toward, each other. grazing animal animal that feeds on grasses, trees, and shrubs. Great Lakes Noun largest freshwater bodies in the world, located in the United States and Canada. Lake Huron, Lake Ontario, Lake Michigan, Lake Erie, and Lake Superior make up the Great Lakes. Great Plains grassland region of North America, between the Rocky Mountains and the Mississippi River. headwater biological family of primates, including humans, chimpanzees, gorillas, and orangutans, and their ancestors. Horn of Africa Noun large peninsula in northeast Africa, including the countries of Somalia, Djibouti, Eritrea, and Ethiopia. Also called the Somali Peninsula. ice age Noun long period of cold climate where glaciers cover large parts of the Earth. The last ice age peaked about 20,000 years ago. Also called glacial age.

ice core sample of ice taken to demonstrate changes in climate over many years. ice sheet rock formed by the cooling of magma or lava. Indian subcontinent landmass in south-central Asia carried by the Indian tectonic plate, including the peninsula of India. indicate characteristic to or of a specific place. industry activity that produces goods and services. iron chemical element with the symbol Fe. island to set one thing or organism apart from others. isthmus tropical ecosystem filled with trees and underbrush. laboratory place where scientific experiments are performed. Also called a lab. landform molten rock, or magma, that erupts from volcanoes or fissures in the Earth's surface. legacy Noun material, ideas, or history passed down or communicated by a person or community from the past. linguistic having to do with language or speech. magma substance used for treating illness or disease. metal category of elements that are usually solid and shiny at room temperature. meteorite a type of large continental island. mist solid material turned to liquid by heat. monsoon Noun seasonal change in the direction of the prevailing winds of a region. Monsoon usually refers to the winds of the Indian Ocean and South Asia, which often bring heavy rains.

landmass that forms as tectonic plates interact with each other. mountain range series or chain of mountains that are close together. navigation tectonic plate currently being formed in western Africa as the African Plate splits in two. ocean region including island groups in the South Pacific. oceanic crust thin layer of the Earth that sits beneath ocean basins. oceanography the way mountains are formed. Outback remote, sparsely populated interior region of Australia. pack ice large area of drift ice, or ice not attached to a shoreline. Pampas flat grasslands of South America. Pangaea supercontinent of all the Earth's landmass that existed about 250 million years ago. peninsula movement and interaction of the Earth's plates. platform Noun ancient rocks that formed as part of continental crust, now overlain with sediment and sedimentary rock, located in the interior of continents. polar having to do with the North and/or South Pole. Polynesia island group in the Pacific Ocean between New Zealand, Hawaii, and Easter Island. precious region Noun any area on Earth with one or more common characteristics. Regions are the basic units of geography. something that is left over.

remote research Noun scientific observations and investigation into a subject, usually following the scientific method: observation, hypothesis, prediction, experimentation, analysis, and conclusion. research station Noun structure or structures built for scientific study of the surrounding region, possibly including residential and lab facilities. rift valley tributaries, mouth, source, delta, and flood plain of a river. savanna type of tropical grassland with scattered trees. sea level Noun rock formed from fragments of other rocks or the remains of plants or animals. shield Noun ancient rocks that formed as part of continental crust and are located in the interior of continents. Siberia region of land stretching across Russia from the Ural Mountains to the Pacific Ocean. snow precipitation made of ice crystals. snowmelt top layer of the Earth's surface where plants can grow. Somali plate tectonic plate currently being formed in eastern Africa as the African plate splits in two. sparse scattered and few in number. stable to be on both sides of an issue, area, or object. subduct to pull downward or beneath something. subduction process of one tectonic plate melting, sliding, or falling beneath another. subduction zone area where one tectonic plate slides under another.

summit to reach the highest point of a mountain. supercontinent ancient, giant landmass that split apart to form all the continents we know today. tectonic plate Noun massive slab of solid rock made up of Earth's lithosphere (crust and upper mantle). Also called lithospheric plate. terrestrial having to do with the Earth or dry land. theorize to formulate and propose a group of ideas to explain a scientific question. tide Noun rise and fall of the ocean's waters, caused by the gravitational pull of the moon and sun. group of islands at the southern tip of South America. tourism the industry (including food, hotels, and entertainment) of traveling for pleasure. trade buying, selling, or exchanging of goods and services. tropical Adjective existing in the tropics, the latitudes between the Tropic of Cancer in the north and the Tropic of Capricorn in the south. unique depression in the Earth between hills. vast all the plant life of a specific place. volcanic island land formed by a volcano rising from the ocean floor. volcano Noun an opening in the Earth's crust, through which lava, ash, and gases erupt, and also the cone built by eruptions.

What Is Pangaea? - Universe Today Universe Today by Jerry Coffey So, you are curious about what is Pangaea? It was the supercontinent that existed 250 million years ago during the Paleozoic and Mesozoic eras. During the ensuing millenia, plate tectonics slowly moved each continent to its current position on the planet. Each continent is still slowly moving across the face of our world. The breaking up and formation of supercontinents appears to have happened several times over Earth’s history with Pangaea being one among many. The next-to-last one, Pannotia, formed about 600 million years ago during the Proterozoic eon. Pannotia included large amounts of land near the poles and only a relatively small strip near the equator connecting the polar masses. 60 million years after its formation Pannotia broke up, giving rise to the continents of Laurentia, Baltica, and Gondwana. Laurentia would eventually become a large portion of North America, the microcontinent of Avalonia(a small portion of Gondwana) would become the northeastern United States, Nova Scotia, and England. All of these came together at the end of the Ordovician.

While this was happening, Gondwana drifted slowly towards the South Pole. These were the early steps in the formation of Pangaea. The next step was the collision of Gondwana with the other land mass. Southern Europe broke free of Gondwana. By late Silurian time, North and South China rifted away from Gondwana and started to head northward across the shrinking Proto-Tethys Ocean. Movement continued slowly until the land masses drifted until their current positions. The list of oceans and microcontinents is too long to include in this article. We have many articles about this full process here on Universe Today. The evidence for Pangaea lies in the fossil records from the period. It includes the presence of similar and identical species on continents that are now great distances apart. Additional evidence for Pangaea is found in the geology of adjacent continents, including matching geological trends between the eastern coast of South America and western Africa. The polar ice cap of the Carboniferous Period covered the southern end of Pangaea. Glacial deposits of the same age and structure are found on many separate continents which would have been together in the continent of Pangaea. We know that the existence of supercontinents has been proven.

We know that they have existed at different times in the Earth’s history. Also, we know that the tectonic plates are still moving. Is it possible that there will be another supercontinent someday in the distant future. We have written many articles about Pangaea for Universe Today. Here’s an article about the Continental Drift Theory , and here’s an article about the continental plates. If you’d like more info on Pangaea, check out the Pangaea Interactive Map Game . And here’s a link to NASA’s Continents in Collision: Pangaea Ultima . We’ve also recorded an episode of Astronomy Cast all about Plate Tectonics. Listen here, Episode 142: Plate Tectonics . Sources:

Question: What name is given to the Earth's single continent, which existed 250 million years ago?
Answer: Pangaea